title: EGO-1, a C. elegans RdRP, modulates gene expression via production of mRNA-templated short antisense RNAs.
abstract: BACKGROUND
  The development of the germline in Caenorhabditis elegans is a complex process involving the regulation of thousands of genes in a coordinated manner. Several genes required for small RNA biogenesis and function are among those required for the proper organization of the germline. EGO-1 is a putative RNA-directed RNA polymerase (RdRP) that is required for multiple aspects of C. elegans germline development and efficient RNA interference (RNAi) of germline-expressed genes. RdRPs have been proposed to act through a variety of mechanisms, including the posttranscriptional targeting of specific mRNAs, as well as through a direct interaction with chromatin. Despite extensive investigation, the molecular role of EGO-1 has remained enigmatic.
  
  
  RESULTS
  Here we use high-throughput small RNA and messenger RNA sequencing to investigate EGO-1 function. We found that EGO-1 is required to produce a distinct pool of small RNAs antisense to a number of germline-expressed mRNAs through several developmental stages. These potential mRNA targets fall into distinct classes, including genes required for kinetochore and nuclear pore assembly, histone-modifying activities, and centromeric proteins. We also found several RNAi-related genes to be targets of EGO-1. Finally, we show a strong association between the loss of small RNAs and the rise of mRNA levels in ego-1(-) animals.
  
  
  CONCLUSIONS
  Our data support the conclusion that EGO-1 produces triphosphorylated small RNAs derived from mRNA templates and that these small RNAs modulate gene expression through the targeting of their cognate mRNAs.
authors.affiliation: Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Jay M
authors.initials: JM
authors.lastname: Maniar
authors.forename: Andrew Z
authors.initials: AZ
authors.lastname: Fire
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000032:analysis*; D034741:RNA, Small Interfering / Q000096:biosynthesis* / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D017423:Sequence Analysis, RNA
chemical_list: D029742:Caenorhabditis elegans Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C406772:EGO-1 protein, C elegans; D012324:RNA-Dependent RNA Polymerase